Portion of a shoe midsole



FIG. 1 is a front perspective view of a portion of a shoe midsole showing my new design.

FIG. 2 is a rear perspective view thereof; and,

FIG. 3 is a side view thereof.

The uneven broken lines immediately adjacent portions of the shaded areas represent unclaimed boundaries of the design. The uneven broken line showing of the remainder of the shoe is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a portion of a shoe midsole, as shown and described. 